CHAPTER IUNITS AND STANDARDS OF MEASUREMENTTo express tlie magnitude of anything, we use in general a number and a name. Thus Ave speak of a length of 3 feet, a temperature difference of 18 degrees, and so forth. The name is the name of the unit in terms of which the magnitude is measured, and the number gives the number of times this unit is contained in the given magnitude. The selection of the unit in each case is arbitrary, and regulated solely by our convenience. In different countries different units of length are in vogue, and even in the same country it is found convenient to adopt sometimes one unit, sometimes another. Lengths, for example, when very great are expressed in miles; when small, in inches: and we also find in use the foot and yard as units for intermediate lengths. Such units as these British measures of length were fixed by custom and convention, and for the purposes of everyday life are convenient enough. When we come, however, to the discussion of scientifiTable of Contents CHAPTER I; PAGE; Units and Standards of Measurement 1; CHAPTER II; The Atomic Theory and Atomic Weights 8; CHAPTER III; Chemical Equations 22; CHAPTER IV; The Simple Gas Laws 27; CHAPTER V; Specific Heats 30; CHAPTER VI; The Periodic Law; 38; Solubility; CHAPTEE VII; CHAPTER VIII; Fusion and Solidification 60; CHAPTER IX; Vaporisation and Condensation 73; CHAPTER X; The Kinetic Theory and Van Der Waals's Equation 84; CHAPTER XI; The Phase Rule 97; CHAPTER XII; Thermochemical Change 117; CHAPTER XIII; Variation of Physical Properties in Homologous Series 127; CHAPTER XIV Relation of Physical Properties to Composition and Constitution 136; CHAPTER XV; PAGE; The Properties of Dissolved Substances 148; CHAPTER XVI; Osmotic Pressure and the Gas Laws for Dilute Solutions 158; CHAPTER XVII; Deductions from the Gas Laws for Dilute Solutions 169; CHAPTER XVIII; Methods of Molecular Weight Determination